Hi Shandy!
Calendars are posted approximately 90 days in advance. I expect the August calendars to be posted in early May.
You'll find the weather to be hot and humid when visiting Walt Disney World in August. Your boys will probably want to spend a lot of time in the pools! As far as visiting the parks, I would recommend you start early, which should be the coolest part of the day. Make sure you all stay well hydrated and find air conditioning when you can! Oh, and bring rain ponchos...you can almost count on an afternoon pop up rain storm!
As far as what attractions to see, you know your boys likes/dislikes best. You may want to spend some time researching the
attractions on disneyworld.com and map out the must dos. There really is so much to see and do!
Also, if your boys have a favorite character they want to see, you may want to see if there is a character dining meal available. You'll find it much more relaxing to sit in an air conditioned restaurant and the the characters come to you vs. standing in the hot sun waiting to see the characters.
I hope this helps...please let us know if you have more questions. Diane :)